Final answer:
The Limited Test Ban Treaty, signed by President Kennedy, outlawed nuclear testing in the atmosphere and outer space.
Step-by-step explanation:
The Limited Test Ban Treaty, signed by President Kennedy on August 5, 1963, outlawed nuclear testing in the atmosphere and outer space. It was signed by the United States, the Soviet Union, and Great Britain. This treaty was an important step towards reducing the environmental and health risks associated with nuclear testing.